package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.conditions.query.QueryChainWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Resource
    private IShopService shopService;

    /**
     * 根据ID查询商铺信息
     *
     * @param id
     * @return
     */
    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop = queryWithPassThrough(id);
        //cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        Shop shop = cacheClient.queryWithLoginExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L, TimeUnit.SECONDS);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        //然后返回
        return Result.ok(shop);
    }


    /**
     * 修改商铺信息
     *
     * @param shop
     * @return
     */
    @Override
    @Transactional
    public Result update(Shop shop) {
        //判断id是否为空
        if (shop.getId() == null) {
            return Result.fail("店铺id不能为空");
        }
        //如果不是为空就修改数据库
        updateById(shop);
        //然后删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return Result.ok();
    }

    /**
     * 根据类型查询商铺信息
     *
     * @param typeId
     * @param current
     * @param x
     * @param y
     * @return
     */
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //判断是否要根据地理坐标查询
        if (x == null || y == null) {
            // 根据类型分页查询
            Page<Shop> page = shopService.query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        //查询redis，按照距离排序，分页。结果：shopId、distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()
                .search(key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        //解析出ID
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }

        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();

        if (list.size() <= from) {
            //没有下一页了，结束
            return Result.ok(Collections.emptyList());
        }

        //截取from-end的部分
        List<Long> ids = new ArrayList<>(list.size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            //获取店铺ID
            String shopId = result.getContent().getName();
            ids.add(Long.valueOf(shopId));
            //获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopId, distance);
        });

        //根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }

   /*
     * 缓存穿透解决方法
     *
     * @param id
     * @return
     *
    public Shop queryWithPassThrough(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.通过提交的ID查询redis中是否存在
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.命中后判断是否为存在
        if (StrUtil.isNotBlank(shopJson)) {
            //5.如果存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if (shopJson != null) {
            return null;
        }
        //3.如果未命中，查询数据库
        Shop shop = getById(id);
        //4.判断数据库中id是否存在，如果不存在报错
        if (shop == null) {
            //5.如果数据库中不存在，不仅返回错误信息，还要将空值写入redis中，避免缓存穿透
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //5.如果存在将数据保存到redis中
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //6.然后返回
        return shop;
    }*/


    /*
     */
/**
 * 缓存击穿互斥锁解决办法
 *
 * @param id
 * @return
 *//*

    public Shop queryWithMutex(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.通过提交的ID查询redis中是否存在
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.命中后判断是否为存在
        if (StrUtil.isNotBlank(shopJson)) {
            //2.如果存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //3.判断命中的是否是空值
        if (shopJson != null) {
            return null;
        }
        //4.实现缓存重建
        //4.1获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2判断锁是否获取成功
            if (!isLock) {
                //4.3失败休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }

            //获取锁成功做DoubleCheck 再次检查缓存，如果存在则无需重建
            shopJson = stringRedisTemplate.opsForValue().get(key);
            if (StrUtil.isNotBlank(shopJson)) {
                //5.如果存在，直接返回
                return JSONUtil.toBean(shopJson, Shop.class);
            }

            //6.如果未命中，查询数据库
            shop = getById(id);
            //模拟重建
            Thread.sleep(200);
            //7.判断数据库中id是否存在，如果不存在报错
            if (shop == null) {
                //7.1如果数据库中不存在，不仅返回错误信息，还要将空值写入redis中，避免缓存穿透
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //8.如果存在将数据保存到redis中
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //9.释放互斥锁
            unLock(lockKey);
        }

        //10.然后返回
        return shop;
    }

    //线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    */
/**
 * 逻辑过期解决缓存击穿
 *
 * @param id
 * @return
 *//*

    public Shop queryWithLoginExpire(Long id) {
        String key = CACHE_SHOP_KEY + id;
        //1.通过提交的ID查询redis中是否存在
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.命中后判断是否为存在
        if (StrUtil.isBlank(shopJson)) {
            //3.如果不存在，直接返回
            return null;
        }
        //命中后需要判断逻辑过期时间
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        if (redisData.getExpireTime().isAfter(LocalDateTime.now())) {
            //如果未过期，直接返回
            return shop;
        }
        //如果过期尝试获取锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        if (isLock) {
            //获取锁成功，再次检测redis缓存是否过期
            shopJson = stringRedisTemplate.opsForValue().get(key);
            if (StrUtil.isBlank(shopJson)) {
                return null;
            }
            redisData = JSONUtil.toBean(shopJson, RedisData.class);
            shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
            if (redisData.getExpireTime().isAfter(LocalDateTime.now())) {
                return shop;
            }
            //如果获取锁成功，开启独立线程执行缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    saveShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unLock(lockKey);
                }
            });
        }
        //如果获取失败，直接返回旧信息
        return shop;
    }

    */
/**
 * 尝试获取锁
 *
 * @param key
 * @return
 *//*

    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    */
/**
 * 释放锁
 *
 * @param key
 *//*

    private void unLock(String key) {
        stringRedisTemplate.delete(key);
    }

*/

    /**
     * 缓存预热
     *
     * @param id
     * @param expireSeconds
     */
    public void saveShop2Redis(Long id, Long expireSeconds) throws InterruptedException {
        //先查询商铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //封装商铺数据
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }
}
